Background:Evidence has accumulated since the mid 1960s from a number of different countries indicating an association between mental disorder and crime and particularly between the major mental disorders and violence. Registries in Denmark were used to identify a birth cohort and to document all psychiatric admissions and all criminal proceedings of the 324 401 members of this cohort up to the age of 43 years.

Methods:Persons who had been admitted to a psychiatric ward were assigned to a diagnostic category according to a hierarchy of principal discharge diagnoses. They were compared with persons never admitted to a psychiatric ward as to the prevalence, type, and frequency of criminal convictions.

Results:Women and men who had been hospitalized in psychiatric wards were more likely to have been convicted of a criminal offense than persons with no history of psychiatric hospitalization. The offenders who were hospitalized committed all types and, on average, as many offenses as did the never-hospitalized group of the same sex.

Conclusions:These findings confirm those from 2 other post-World War II Scandinavian birth cohorts that have found an association between psychiatric hospitalization and criminal convictions. They also concur with findings that patients discharged from psychiatric wards are more likely than other persons living in the same community to commit crimes and with results from North America showing elevated rates of major mental disorders among incarcerated offenders. Generalization of these findings is limited to nations with similar criminal justice, mental health, and social welfare systems.